It may not look like anything important, but see that adorable little fish in the photo above? It’s a lumpsucker from Norway, and it may hold the answer to one of salmon farming’s most vexing problems: destructive sea lice and the chemicals commonly used to stop them.

Near the tiny island of Indre Kvaroy, just off the central coast of Norway, I recently visited the family-owned salmon farm Kvarøy Fiskeoppdrett, which has been using those sweet little lumpsuckers instead of chemicals or pesticides to keep their salmon pens free of sea lice—and so far, the results look promising.

If the term "lice," sea or not, has you crinkling your nose, you’d be justified. Sea lice are marine parasites that attach themselves to other host fish—in this case, salmon—typically feeding off the mucus and skin of the fish, and possibly lowering the salmon’s immune system, leaving it susceptible to other diseases. Environmentalists say it’s the transfer of sea lice from farmed salmon to wild salmon that can threaten the health of wild stocks.

The pesticide most commonly added to salmon feed to prevent sea lice is emamectin benzoate, more widely known by its brand name, SLICE. Once in the feed, the drug is absorbed into the salmon's tissue and transmitted to the sea lice, killing them off. But much in the way that superweeds have evolved over years of continuous pesticide use, or in the way antibiotic resistance is showing up in our food and health systems, sea lice are adapting as well.

“Everywhere it’s the same situation with sea lice,” says Thierry Chopin, professor of marine biology at the University of New Brunswick and scientific director of the Canadian Integrated Multi-Trophic Aquaculture Network. “In Norway, Canada, Chile, and Scotland—everyone was using SLICE for 10 years. The sea lice are not stupid. They found a way to resistance, and now we are cornered.”

The idea of using lumpsuckers, or other related types of wrasse, is fairly recent, but it isn’t as simple as tossing a few of the little guys into a stocked salmon pen.

Lumpsuckers like to hover in long strands of kelp. As the salmon move in and out of the nearby kelp, the lumpsuckers gently bite the sea lice off the salmon. In a way, it’s a little like a symbiotic car wash.

“Not everyone believes it works,” says Gjermund Olsen, cofounder and production manager at Kvarøy Fiskeoppdrett. “If you’re farming with wrasse, you have to do it right. If you drop them in the pen and think it’s your salvation, you’re wrong.”

There’s some frequent maintenance that goes along with them, including keeping the nets clean so the lumpsuckers stay focused on nabbing sea lice and not on eating other snacks that might congregate nearby.

Part of the motivation for Kvarøy Fiskeoppdrett to experiment with lumpsuckers as an alternative to pesticides is its relationship as a supplier to Whole Foods—which funded my reporting trip to Scandinavia—along with the family’s desire to stand out in its farming practices. The grocery chain's aquaculture standards prohibit the use of synthetic pesticides.

Much like an organic farmer in Iowa might be surrounded by farms embracing industrial practices, Kvarøy Fiskeoppdrett is similarly surrounded by corporate operations owned by aquaculture giants Marine Harvest and Nova Sea.

Carrie Brownstein, seafood quality standards coordinator at Whole Foods, says getting producers to embrace solutions other than pesticides like SLICE or chemical bath treatments to rid the salmon of sea lice took time but was important.

“Those kinds of compounds can get into the actual ecosystem, so we really wanted to move away from them,” she says.

And clearly, the natural foods giant is feeling the love for cleaner fish like wrasse and lumpsuckers. Its recently updated producer guidelines mention the chubby fish by name.

While lumpsuckers are native to that part of Norway, Kvarøy Fiskeoppdrett is collaborating with a small group of other salmon farmers to farm lumpsuckers in land-based tanks. This past year, the company used 100,000 of them in its pens to control lice on the approximately 17.6 million pounds of gutted whole fish that the farm produces every year. To put that into perspective, Kvarøy Fiskeoppdrett CEO Alf-Goran Knutsen says his company's fish make up 8 percent of all the salmon Norway exports to the U.S.

“You need a lot of them,” says Olsen. “Sea lice are like a snowball. They spawn and spawn and spawn.”

Bivalves such as mussels, clams, and oysters are filter feeders. And sea lice start their life as small larvae floating in the water column. If strands of bivalves are stationed around a salmon pen, the idea is that they could intercept and ingest the sea lice larvae before they grow big enough to latch on to a salmon or reproduce.

“We know the bivalves don’t just ingest the sea lice; they digest them, so they’re broken down and killed. But can they make a big impact on sea lice at an actual site? It’s one thing to do it in the lab in small containers; it’s another to take it out in the field and see how the shellfish can make a difference in the number of lice at the farm site,” says Pearce.

Tests are under way, and he hopes to have results by this fall.

While all of this seems hopeful, Chopin says he’s not convinced yet that any one technique will be the ultimate silver bullet in the sea lice problem.

“I don’t think chemicals or cleaner fish will address the problem 100 percent. The industry needs a several-pronged approach. Knowing one technique can’t do it all is fine. That’s what happens in nature too,” he says.

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